The present invention relates to a cassette for holding a gel slab used in an electrophoresis separation and, more particularly, to such a cassette as is more easily and surely assembled than heretofore practiced and to an end that fluid leakage laterally of the cassette from a liquid-containing gel slab composition cast in the cassette is prevented.
Separation of biological components by electrophoresis separation is well known. In such a separation, electric current flow through a gel slab carries, e.g., DNA, RNA or protein molecules from a source at a negative terminal through the slab towards a positive terminal, the passage of these molecules being identifiable, observable and recordable so as to produce data meaningful to the molecular biologist.
Commonly the gel slab is formed or cast from a gellable composition such as an acrylamide in a cassette comprised of two glass plates juxtaposed spaced by spacer strips at the sides of the plates. During casting, the bottom side of the cassette generally is sealed by the a seal element carried on a casting stand. The spacer strips can be elements adhesively secured to facing sides of the two glass plates as disclosed, for example, in U.S. Pat. No. 4,699,680. Other spacers commonly are of rigid plastic such as nylon and these are clamped together intermediate the two plates at side margins thereof with devices such as screws or like components in quest of establishing fluid proof interface between the plates and the spacers.
The degree of seal possible with the foregoing arrangement is problematical and often ineffective to the end of leakage of liquid from the gel composition and outwardly from the cassette sides. Such leakage also creates soil conditions on the cassette which are messy and difficult to clean.
Further, aligning edge surfaces of the glass plates and spacers in proper sandwich configuration is tedious and if not done with precision is futile since composition leakage almost certainly will occur during casting and before the composition has gelled. In some instances, technicians have sought to prevent leakage during casting by taping the side edges of the cassette before introducing the gel slab composition therein.